- Eskişehir Teknik Üniversitesi
- Başlangıç Yılı
- Havacılık Dizini, TRDizin
- Yayın Aralığı
Son Sayı (Latest Issue) - Year 2022 Volume 23 Issue 4
In this study removing heavy metals, Cr (III), and Pb (II) from wastewater, Microorganism Trichoderma sp. biosorption was performed using Cr (III), and Pb (II) removal was taken into account. For this study, 3^3 Factorial Experiment Designs were used, and temperature (°C), biosorbent dosage (g/L), and pH were selected as the main factors for Cr (III), and Pb (II) metals and three levels of these factors were determined as low, medium, and high. In this study, which was carried out to increase the metal removal efficiency and biosorption capacity, the main factors and the significance of each interaction of these factors were examined with 3^3 Factorial Design. For this purpose, by conducting Analysis of Variance (ANOVA) via Response Surface Methodology and optimization, more detailed results were obtained regarding the factors affecting the efficiency of metal removal from wastewater.
While the increase in the customer failure rate in the consumer electronics sector affects the manufacturers negatively in terms of cost. It has also become one of the issues that cause customer loss and customer satisfaction. In addition to the economic losses, during the production and distribution of the spare parts and products that are changed at the customer's home due to the reliability problems experienced in the field, extra carbon emissions are released to the nature for this operation. For these reasons, it has become important to reduce the rate of customer failure. With the increase in electronic components, the quality and reliability precautions that may occur in the electronic circuits, have become the subject of study today. As in many white goods products, it is advantageous to have variable speed motors in refrigerators due to energy efficiency and energy regulation issues. For this reason, the compressor of refrigerator comes to the forefront as the component that dissipates the highest power proportionally. With the use of variable speed compressors, the need for an electronic board with including power conversion and motor driving capability has arisen. In this paper, RC Snubber circuits have been studied in order to prevent quality problems that may occur due to high switching frequency in flyback converter topology, which is one of the DC-DC converters that provide isolation. The methods in the literature based on the location of the RC Snubber in the circuit and the determination of its related values were examined and experiments were made on the simulation program. At the same time, a test mechanism was set up on the variable speed compressor motor control card of the refrigerator and measurements were taken with the help of an oscilloscope. The measurements taken in the simulation program and the experimental environment were compared.
UV-curable thermoset resins had been utilized in organic coating industry because of their benefits over conventional adhesives like fast curing, less energy consumption and equipment. In this article, the effects of micro and nano-scaled reinforcements on the mechanical properties of a UV-curable thermoset resin were investigated. The reinforcements are chosen to be nano-scaled Montmorillonite (MMT) and micro-scaled Silica (SiO2). The reason for this choice is that the aforementioned particles are non-toxic, low-cost and in the case of MMT; abundant in nature. According to our knowledge, there is no study on the synergistic effects of those two additives in thermoset resins. The instrumented microindentation test results reveal that maximum improvement on hardness (288%) was achieved by single addition of MMT thanks to the well-distributed silicate layers. Conversely, SiO2 addition diminished both strength (-51%) and modulus (-68%) drastically which is attributed to the possible poor dispersion and weak surface attraction. On the other hand, when those additives were utilized together, the property improvements namely; hardness and modulus are observed to be in between of single addition of either additive. It is suggested that SiO2 contribution does not disturb intercalated/exfoliated-MMT structure and similarly by simultaneous MMT reinforcement, quality of SiO2 dispersion is not affected. It is concluded that one benefit of these SiO2-MMT combinations over single MMT reinforcement could be related to plasticity since they result in less plasticity reduction of -22%-27% compared to MMT (-43%) with the further benefit of higher hardness improvement (+66%) than bare SiO2 addition (-51%).
Aerospace-grade carbon fiber reinforced polymer composite plates with four different fiber orientations 0º, 30º, 45ºand 60º is produced with the autoclave curing method and subjected to tensile testing. The stress-strain curves of the composite specimens are compared with Hooke’s law. It is observed that Hooke’s law coincides precisely with the experimental results for samples containing fibers parallel to the loading direction. However, it does not coincide with samples where the fibers make a certain angle with the applied load direction.. Moreover, it is reported that Hooke’s law converges the experimental results for small strain values but diverges significantly from the experimental results at higher strain values.